Turbochargers commonly include a turbine and a compressor linked by a shared rotating shaft. The turbine inlet receives exhaust gases from the engine exhaust manifold causing the turbine wheel to rotate. This rotation drives the compressor, compressing ambient air and delivering it to the air intake of the engine, resulting in a greater amount of the air (for a diesel engine, or air/fuel mixture for a natural gas or gasoline engine) entering into the cylinder. Due to the balance of pressure inside the turbocharger, a considerable axial force tends to push the rotating shaft in the direction of the compressor. These forces are absorbed by the thrust bearing. In addition, under certain conditions of rotating group instability (for example early stages of journal bearing wear or failure), radial forces can be generated. Such radial forces, and other transverse forces which act prior to the radial forces, can result in severe damage to the turbocharger.
Some conventional systems attempt to detect the presence of these radial forces, however these systems do not attempt to detect the earlier presence of transverse forces between the shaft and interior components of the turbocharger, and thus significant damage could have already occurred to the turbocharger. Additionally, some conventional systems do employ speed sensors with the rotating shaft, however these systems do not use these speed sensors to determine whether transverse forces are present.
Thus, it would be advantageous to provide an early warning detection system to monitor the radial motion of the rotating shaft of the turbocharger and/or the presence of these transverse forces, prior to the onset of any damage to the turbocharger. Such a system may, for example, initially determine the early onset of transverse forces (sensed as excessive radial shaft motion) exerted on the rotating shaft, thereby preventing subsequent damage caused by axial forces.